From: Chris Lattner <sabre@nondot.org>
Date: Thu, 19 Jan 2006 07:40:22 +0000 (+0000)
Subject: Implement casts.ll:test26: a cast from float -> double -> integer, doesn't
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=bc528efa76e8d0f225630e4677c8e74d17f23fc5;p=oota-llvm.git

Implement casts.ll:test26: a cast from float -> double -> integer, doesn't
need the float->double part.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@25452 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp
index 2fcf9194846..f440e475e0b 100644
--- a/lib/Transforms/Scalar/InstructionCombining.cpp
+++ b/lib/Transforms/Scalar/InstructionCombining.cpp
@@ -3799,8 +3799,8 @@ static CastType getCastType(const Type *Src, const Type *Dest) {
 // isEliminableCastOfCast - Return true if it is valid to eliminate the CI
 // instruction.
 //
-static inline bool isEliminableCastOfCast(const Type *SrcTy, const Type *MidTy,
-                                          const Type *DstTy, TargetData *TD) {
+static bool isEliminableCastOfCast(const Type *SrcTy, const Type *MidTy,
+                                   const Type *DstTy, TargetData *TD) {
 
   // It is legal to eliminate the instruction if casting A->B->A if the sizes
   // are identical and the bits don't get reinterpreted (for example
@@ -3856,6 +3856,15 @@ static inline bool isEliminableCastOfCast(const Type *SrcTy, const Type *MidTy,
       return ResultCast == FirstCast;
     }
   }
+  
+  // If this is a cast from 'float -> double -> integer', cast from
+  // 'float -> integer' directly, as the value isn't changed by the 
+  // float->double conversion.
+  if (SrcTy->isFloatingPoint() && MidTy->isFloatingPoint() &&
+      DstTy->isIntegral() && 
+      SrcTy->getPrimitiveSize() < MidTy->getPrimitiveSize())
+    return true;
+  
   return false;
 }